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Hazard controls: dust protection for bag stackers.

Mineral processing plants in the United States and throughout the world process material that is finely ground and placed into bags for shipping to the consumer. These bags normally range from 50 to 100 pounds in weight. Once the material is placed in these bags, a bag stacker loads the bags onto pallets. A bag stacker is exposed to a lot of dust that is mainly released by the force from loading the bag onto the pallet. The two main sources are the dust on the outside of the bag and the dust that escapes from inside the bag as it is loaded. The Mine Safety and Health Administration's (MSHA) records indicate the bag stacker's dust exposure is one of the highest of all workers at mineral processing operations. Ways to reduce the dust exposure and strain to the bag stacker are in constant development. Recently, automated systems have been built. These systems range from fully automated, which totally remove the worker from the bagstacking process, to semi-automated, in which the bag stacker still performs some of the functions. This hazard control deals with controlling the bag stacker's dust exposure during use of a semi-automated palletizing machine. The worker slides the bags into position on the palletizing machine. Once an entire layer of bags is positioned, the bag stacker operates the controls on the palletizing machine to lower the layer of bags onto the pallet. An air slide is built into the semi-automated palletizing machine so the bags are easier to move. This slide uses a metal table with air jets that exit through small holes at high velocities, similar to an air hockey game. The dust problem occurs because the air slide causes dust to blow up onto the bag stacker, significantly increasing the dust exposure. The key to lowering the bag stacker's dust exposure to MSHA-acceptable concentrations was to make a few simple changes and to slightly modify the bag stacker's work habits. The bag stacker had been leaning out over the air slide table and placing his upper torso in the front part of the exhaust ventilation system capture hood. Therefore, NIOSH researchers suggested that the exhaust hood be modified to make it physically impossible for the bag stacker to place his or her upper torso into the hood.